The present invention relates to a rectangular AT-cut quartz resonator, and more particularly to a rectangular AT-cut quartz resonator of miniature size, wherein spurious or unwanted resonance frequencies are remote from the main thickness-shear resonance frequency to thereby improve the quality factor of the main resonance and the frequency-temperature characteristics of a resonnce frequency.
Conventionally, AT-cut quartz resonators have been in popular use in communication instruments or the like on account of superior frequency-temperature characteristics, a high quality factor and a low equivalent resistance.
The AT-cut resonators conventionally used are disk shape in general, and the dimensional ratio of diameter to thickness is large and scarcely influenced by spurious resonances. However, as for a quartz resonator of miniature size for use in a wrist watch, since the coupling between thickness-shear resonance and the spurious resonances is strong, the quality factor and the frequency-temperature characteristics of the quartz resonator exceedingly deteriorate. Particularly, as for a small rectangular AT-cut quartz resonator already published in literature and the like, a mass-producible and practical one has not been obtained under the present conditions.